In the so-called "by infusion" process, the mash mixture is then sent into a saccharification device normally constituted by a vat called a mush-tub in which the temperature is raised in steps to produce thhe saccharification of the starch, i.e., its conversion into dextrin and into maltose under the influence of the enzymes of the malt.
In the process called "extract decoction", a portion of the mixture is heated separately in a tank called a "mash copper" and then brought back into the mash-tub whose temperature rises. The same operation is repeated two or three times to bring the mixture in the mash-tub to a temperature of 70.degree. to 75.degree. C., the saccharification process thus occurring progressively.
The must wort thus obtained when undergoes successive operations of filtration, cooking and hopping before fermentation, it is unnecessary to describe these in detail.
In certain countries, the beer must be manufactured solely from barely malt. However, it is possible to replace a portion of the malt by a substitution product of which the saccharification is ensured, after mashing, by the enzymes of the malt. This substitution product, often called "unmalted grain" or "raw grain", may be constituted by a cereal such as broken rice or corn grits.
In this case, parallel with the line of preparation of the malt, there is placed a line of preparation of the raw grain which, at the outlet from the silos, comprises a crusher, a pre-masher which can be constituted by the converter used for the mashing of the malt, and a "mash copper". In fact, before using subjected to the action of the malt in the saccharification operation, the raw grain must be cooked separately to effect the thickening of the starch that it contains. This is why the brewing process by decoction described above for the malt is used.
The crude grain, previously mashed in the converter, is mixed in the mash copper with warm water and with a portion of the contents of the mash-tub which contributes the hydrolyzing enzymes. The mash of raw grain thus prepared then undergoes boiling, which effects the bursting of the starch particles, and it is then brought back into the mash-tub whose temperature is increased on each addition of a mash and whence the saccharification is produced on contact with the rest of the malt.
Local legislation can limit the proportion of crude grain used for the manufacture of the beer. Thus, in France, this proportion is limited to 30%. However, even in countries where the legislation does not impose a maximum percentage of raw grain, a proportion of 45% cannot generally be exceeded for the manufacture of a correct beer based on malt since, beyond this proportion, the saccharification of the starch does not occur under good conditions.
On the other hand, when rice is used, it is observed that certain qualities of rice produced at present thicken poorly, which increases the content of malt that must be used.